Organism and Its Environment

ORGANISM AND ITS ENVIRONMENT The entirety of living and non-living elements, substances, and circumstances that encircle and potentially pester organisms without integrating into them. The orbit of our planet around the Sun and the tilt of its axis bring about yearly changes in the strength and length of temperature, leading to different seasons. These changes, along with yearly fluctuations in rainfall (remember, rainfall includes both rain and snow), contribute to the creation of significant biomes like deserts, rainforests, and tundra. Terrestrial Biomes Tundra Taiga (coniferous forest) Temperate forest Grasslands (i) Temperate grassland (ii) Tropical savanna grassland (grass cover with scattered trees) Desert Tropical rain forest [Image of a graph showing the distribution of different biomes based on mean annual temperature and precipitation.] Figure - Biome distribution with respect to annual temperature and precipitation Major biomes of India: 1. Tropical rain forest 2. Deciduous forest 3. Desert 4. Sea cost We believe that over time, the organism has developed adaptations through natural selection to improve its chances of surviving and reproducing in its environment. Each organism has a specific range of conditions it can endure, uses diverse resources, and plays a unique role in the ecological system. Altogether, these factors make up its niche. Environmental Factors: They directly or indirectly affect the form and functioning of organisms in any specific way. They are two types. Abiotic Factors Biotic Factors Major Abiotic Factors Abiotic Factors: They are of four types. (1) Climatic (2) Edaphic (3) Topographic (4) Fire (1) Climatic Factors: Light, temperature, humidity, air, precipitation, involve in this category. Light: Sunlight is the main natural source of light. About 1% of light coming from the sun is utilized by plants. The visible range of electromagnetic spectrum is about 390 nm to 760nm. Out of them wavelength of photo synthetically active radiation (PAR) is 400-700 nm that is effective in photosynthesis in plants. Solar constant: Just before entering the mesosphere, the energy content of solar radiations is 2 Cal/cm² /min. Sunlight involves ultraviolet rays, light spectrum and infrared rays. Ultraviolet rays are of three types S.No. Type of UV rays Wavelength of UV rays 1 2 UV-B 280 - 320 nm 3 UV-A 320 - 400 nm UV-C rays are deadly, and UV-B rays are quite harmful. The ozone layer absorbs UV-C and half of UV-B radiation. Light sets many activities such as photosynthesis, growth, coloration, movements, daily rhythms in animals, and response to day length. Plants rely on sunlight for photosynthesis, which produces food using sunlight as energy. This highlights the importance of light for living organisms, especially autotrophs. Some small plants in forests have adapted to low-light conditions because they are shaded by tall trees. Many plants also need sunlight to trigger flowering. Animals use light cues for timing activities like feeding, breeding, and migration. Light availability on land is closely tied to seasons, since the sun's angle changes both. However, deep in the ocean (>500m), it is dark, and marine organisms don't have access to sunlight. Their source of energy is different. The type of sunlight, including UV radiation, affects life in the ocean. UV rays can harm many organisms, and not all colors of visible light are available at different depths. Among red, green, and brown algae in the ocean, which is likely to be found deepest? And why? Temperature: Temperature is a crucial environmental factor that influences where many plants and animals live and affects their bodily functions like enzyme activity. You know that land temperatures change with the seasons, decrease as you move from the equator to the poles, and from lowlands to high mountains. Temperatures vary widely, from freezing in Polar Regions and high altitudes to over 50°C in deserts during summer. However, there are exceptional places like hot springs and deep-sea vents where temperatures surpass 100°C. It's common knowledge that mango trees can't grow in places like Canada and Germany, snow leopards aren't found in Kerala forests, and tuna fish are rarely found beyond the tropical regions of the ocean. v. Echolocation : Bats emit high-frequency sounds that bounce off objects and return as echoes, using a principle similar to sonar. These echoes help bats navigate and understand their surroundings, guiding them along their flight path. vi. Adaptation of water Scarcity: Animals living in arid or desert regions possess two main types of adaptations: 1. They can endure dry conditions. 2. They can assimilate water from food. For instance, the Kangaroo rat, also known as the Desert Rat, rarely drinks water. It obtains 90% of its required water from metabolic processes, while the remaining 10% comes from its food. Similarly, camels exhibit various adaptations to survive in such harsh environments. vii. Phenotypic adaptations : In various wild organisms, certain physical adaptations develop to respond to unfavorable conditions. For example, humans often experience altitude sickness at high altitudes (above 3500 meters). Symptoms may include nausea, fatigue, and heart palpitations due to the low atmospheric pressure at high altitudes. To cope with the reduced oxygen availability, the body increases the production of red blood cells, decreases the binding capacity of hemoglobin, and elevates the breathing rate. viii. Hibernation and Aestivation: Ectothermal (cold-blooded) animals like frogs exhibit hibernation (winter sleep) and aestivation (summer sleep) to regulate their body temperature. Certain organisms use behavioral responses to adapt to changes in their environment. For instance, desert lizards lack the physiological mechanisms mammals have to cope with high temperatures, but they maintain a relatively constant body temperature through behavior. They can sunbathe to absorb heat when they feel too cold, but seek shade when temperatures rise. Some species can burrow into the soil to escape the heat above ground. Temperature gradient over earth's surface is called lapse rate that is 6.4 - 6.5°C per 1000m altitude. On the basis of occurrence in different climatic zones, the plants are classified into four groups, according to their surrounding temperature: (i) Megatherms: In this zone, plants grow in high temperature throughout the year. E.g. Tropical rain forest (ii) Mesotherms: Growth of plants takes place in alternate high and low temperature e.g. Tropical deciduous forest. (iii) Microtherms: Plants grow in low temperature e.g. temperate needle forest. (iv) Hekistotherms: Plants grow in very low temperature e.g. alpine vegetation. On the basis of ability of organisms to tolerate variations in surrounding temperature, organisms are of two types. (i) Stenothermal They live within narrow range of temperature throughout the year. E.g. Polar Bear, lizards, amphibians, plants like-Neem, Abies, and coconut. (ii) Eurythermal These organisms can tolerate a wide range of temperature variations, e.g. most mammals & birds. Effect of Temperature on animals: (i) Allen's Rule: Extremities like tail, ears, feet of animals of colder areas are shorter then Animals of warmer areas. (ii) Bergaman's Rule: Birds and mammals of colder areas are larger in size as compared to their equivalents in warmer areas. (iii) Gloger rule: Homeothermal animals of tropical region or hot and humid area are darker in colour than cold area. Thermoperiodicity ; Regular change in temperature at spacific intervals of time is called thermoperiodicity it involves two types (a) **Diurnal Thermoperiodicity:**Temperature is higher during the day and cooler during night. The response of organisms to change of temperature is called diurnal thermoperiodicity. (b) Seasonal Periodicity: It contains sharp difference temperature in different seasons of the year.That is called seasonal periodicity that favour different aspects of plants and animal life or phenology. Thermal stratification in lakes ; (i) Epilimnion: It is upper zone of water body. It is warmer in summer and colder in winter. (ii) Metalimnion: It is found between epilimnion and hypolimnion as traditional zone. It.shows maximum temperature flucuations its middle part is called thermocline. (iii) Hypolimnion: In the lower depths of a body of water, temperatures typically change less. In temperate lakes, oxygen and nutrients circulate twice a year, in spring and autumn, creating conditions for abundant phytoplankton growth. These lakes are known as dimictic. Phytoplankton thrive when surface water is warm in spring and cool in autumn. Conversely, there's minimal phytoplankton growth during summer and winter. Many freshwater animals cannot live for long in sea water and vice versa because of the osmotic problems, they would face. (c) Water Water is one of the most crucial factors affecting organisms' lives. Life originated in water and cannot exist without it. In deserts, water is scarce, and only specialized adaptations allow organisms to survive there. Plant productivity and distribution heavily rely on water availability. While you might assume that organisms in oceans, lakes, and rivers don't face water-related issues, that's not the case. For aquatic organisms, water quality, including chemical composition and pH, is vital. The salt concentration, known as salinity, varies: it's less than 5 in freshwater; around 30-35 in seawater; and over 100 in some hypersaline lagoons. Some organisms can tolerate a wide range of salinities (euryhaline), while others can only survive in a narrow range (stenohaline). Many freshwater animals can't survive in seawater for long, and vice versa, due to osmotic challenges they'd encounter. Soil or Edaphic Factor Soil The top layer of the Earth's crust is formed by the weathering of rocks, consisting of a mixture of living and non-living materials. The nature and properties of soil vary depending on factors such as climate, weathering processes, transportation or sedimentation, and soil development. Characteristics like soil composition, grain size, and aggregation affect how water moves through the soil and its ability to retain water. These features, along with factors like pH, mineral composition, and terrain, largely determine the vegetation in an area, which in turn influences the types of animals that can live there. Similarly, in aquatic environments, sediment characteristics often determine the types of benthic animals that can thrive. Soil consists of minerals (45%), water (25%), air (25%), and organic matter (5%). Soil formation is a slow process, with just one inch of soil forming over 500-1000 years. Pedagenesis – development of soil or soil formation Pedology (Edaphology) – study of soil Soil mineral matter - As a result of weathering the mineral particles of different size are formed. The soil is divided into types in the basis of size of soil particles. Soil Type Size of particles Clay < 0.002 mm Silt 0.002 – 0.02 mm Fine sand 0.02 – 0.20 Coarse sand 0.20 – 2.0 Gravel of Grit 2mm – 5mm Coarse Gravel Above 5.00 Sandy Soil = 85% sand + 15% clay or silt or both Loamy Soil = 50% sand + 50% clay or silt or both Silt Soil = 90% silt + 10% sand Note Loam Soil is the best soil for growing of crops due to high water holding capacity, high aeration and high root penetration.